// This proram version should make use of the Abstract Data Object paradigm (ADO).
// There shoud be an abstract data object module. Its only and implicitly created
// instance is the abstract data object random_number_generator. It is not allowed
// to create further instances of the abstract data object module.
// Data of the ADO shall not be accessible from outside. There should be appropriate
// functions with public access for the relevant functionality of rando_number_generator.
// You should avoid any global variables.

#include <iostream> // required for console input and output
#include <chrono> //required for getting system time

using namespace std; // allows unqualified use of identifiers of namespace std

// The following free function should remain as is.
// It would be pointless to encapsulate it as an ADO.
bool ask_yn(const char * msg) {
    cout << msg << " (y/n)? " << flush;
    char answer;
    cin >> answer;
    if (answer == 'y' || answer == 'Y')
        return true;
    else return false;
}

// The solution is to have a class with static attributes and static methods only.
class random_number_generator {
private:
    static unsigned long int max,
    factor,
    increment,
    start,
    actualrandom;
public:
    static unsigned int long random_number() {
        actualrandom = ((factor * actualrandom) + increment) % max;
        return actualrandom;

    }
    static void random_seed() {
        // the following function calls retrieve system time and cast it to milliseconds
        actualrandom =  chrono::duration_cast<chrono::milliseconds>(chrono::system_clock::now().time_since_epoch()).count();
    }
};

// Due to C++ requirements static attributes have to be initialized outside the class.
unsigned long int random_number_generator::max = 1000;
unsigned long int random_number_generator::factor = 623;
unsigned long int random_number_generator::increment = 525;
unsigned long int random_number_generator::start = 157;
unsigned long int random_number_generator::actualrandom = ((random_number_generator::factor * random_number_generator::start) + random_number_generator::increment) % random_number_generator::max;;


int main(int argc, const char * argv[]) {
    if (ask_yn("Random seed the generator") == true)
        random_number_generator::random_seed();
    do {
        cout << random_number_generator::random_number() << endl;
    } while (ask_yn("Another random number") == true);
    return 0;
}